Roger Halstead wrote in message . ..
On 20 Dec 2003 15:47:22 -0800, (LakeCapt)
wrote:

I'm not sure I follow all this and maybe I'm missing what you are
asking but...

Sorry I wasn't so clear. You've generally touched on the major
points. The level of surface finish I am suggesting is as follows:

1) Construct a KR wing with an outside surface of one contiguous piece
of foam for the structure in front of the forward spar (the D
section), and a second single contiguous piece of foam between the
front and rear spars.

2) Cut this foam with hotwire from polystyrene similar to
A) Mike's KR wing (Ez-style):
http://www.fortunecity.com/marina/anchor/270/wing.html
or B) Mark's sanded-down urethane method:
http://home.hiwaay.net/~langford/owings.html

3) Sand the foam with a long straigt edge, as shown on Mark's page
(leaving out the joggle around the spar). This should leave a
*relatively* flat substrate/airfoil on which to glass.

4) Glass the wing wing a span-wise layer of glass top and bottom.
When layed-up from root to tip, this removes any possible glass
overlap joggle except on the leading edge.

5) Use peel-ply over the entire glass surface, leaving the fine
reciprocal weave of the Dacron exposed once the peel-ply is removed.
This is roughly the same roughness as your standard rag-and-tube
dacron covered plane (before dope).

6) Paint the wing with a primer like Smooth Prime. This should fill
just a little, and leave a good surface for a top coat.

7) Paint the wing with a final finish, which would provide minimal
filling ability but protect the surface.


So why all this hassle? The alternative is, of course, hundreds of
hours of sanding and filling micro to get that glass finish, which may
take as much time as building the rest of the structure on a plane
like a KR.

If one was happy with a 100mph cruise, this seems like a quick way to
produce a set of wings. The question is, again, is this safe from a
"draggy" surface standpoint on a NACA 4-digit airfoil.


Thanks for your input.